A sedating antihistamine for allergy symptoms
Carbinoxamine
An older sedating antihistamine used to ease allergy symptoms such as a runny nose, sneezing and itching.
What is Carbinoxamine?
Carbinoxamine is an older, sedating antihistamine used to relieve allergy symptoms such as a runny nose, sneezing, watery eyes and itching. It works by blocking histamine, the chemical the body releases during an allergic reaction. Because it is a sedating type, the main thing to expect is drowsiness, and it can also cause antimuscarinic effects such as a dry mouth, blurred vision and constipation. It is largely a US product and is not a usual choice in the UK, where non-drowsy antihistamines are preferred. It is dangerous in very young infants and should not be used in them.
Education and reference only. This is a plain-language guide to Carbinoxamine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Carbinoxamine is one of the older, first-generation antihistamines, the kind that tend to make people drowsy. It is used to ease the symptoms of allergies, such as hay fever and other allergic reactions, including a runny or blocked nose, sneezing, itchy or watery eyes and itchy skin. It is largely a product of the United States and is not a routine medicine in the UK, where newer, non-drowsy antihistamines are usually preferred. It is taken by mouth. Importantly, it can be dangerous in very young infants and is not suitable for them.
How it works
When the body meets something it is allergic to, it releases a chemical called histamine, which causes the runny nose, sneezing, itching and watering that make up allergy symptoms. Carbinoxamine blocks the action of histamine, so these symptoms are eased. Because it is an older antihistamine that crosses into the brain, it also tends to cause drowsiness, and it can produce antimuscarinic effects such as a dry mouth and blurred vision. Newer antihistamines are designed to block histamine without causing as much drowsiness, which is why they are generally preferred.
Company & origin
Originated / developed by: Generic (long-established).
An older sedating antihistamine used mainly in the United States for allergy symptoms; rarely seen in routine UK practice.
What it treats
Conditions Carbinoxamine is used for
Practical use
How to take Carbinoxamine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth as prescribed or directed, and be aware that it commonly causes drowsiness.
- Avoid driving or operating machinery until you know how it affects you, as it can make you sleepy.
- Avoid alcohol and other sedating medicines while taking it, as the drowsy effect adds up.
- Do not give it to very young infants, as sedating antihistamines can be dangerous in babies.
- Tell your prescriber about other medicines you take, especially anything that causes drowsiness or a dry mouth.
Weighing it up
Advantages & disadvantages of Carbinoxamine
Advantages
- Eases allergy symptoms such as a runny nose, sneezing, watery eyes and itching.
- Taken by mouth and long established as a treatment.
- Its sedating effect can sometimes be helpful when allergy symptoms disturb sleep.
Disadvantages
- Commonly causes drowsiness, which can affect driving and daily activities.
- Causes antimuscarinic effects such as a dry mouth, blurred vision and constipation.
- Dangerous in very young infants, and largely a US product not routinely used in the UK.
Practical use
Good to know
The most important things to know about carbinoxamine relate to its sedating nature. It commonly causes drowsiness, so it can affect driving and using machinery, and its effect adds to that of alcohol and other sedating medicines. It also tends to cause antimuscarinic effects, such as a dry mouth, blurred vision, constipation and difficulty passing urine, which can be more troublesome in older people. A crucial safety point is that it is dangerous in very young infants and must not be used in them, as sedating antihistamines can cause serious breathing problems in babies. In the UK it is not a usual choice, and newer non-drowsy antihistamines are generally preferred for allergy symptoms. Tell your prescriber about other medicines, particularly anything that causes drowsiness or has antimuscarinic effects.
Who should not take it / use with caution
- Very young infants must not be given it, as sedating antihistamines can be dangerous in babies.
- People who have had a serious allergic reaction to carbinoxamine should not take it.
- It is used with caution in older people and in those with glaucoma, an enlarged prostate or difficulty passing urine, because of its antimuscarinic effects.
Monitoring
- Reviewing how well allergy symptoms are controlled and how much drowsiness it causes.
- Watching for antimuscarinic effects, especially in older people.
- Checking it remains an appropriate choice rather than a non-drowsy alternative.
Side effects
- Drowsiness, which is common with this type of antihistamine.
- A dry mouth, blurred vision, constipation or difficulty passing urine.
- Dizziness or, occasionally, a feeling of restlessness, particularly in children and older people.
Key interactions
- Alcohol and other sedating medicines add to its drowsy effect, so they should be avoided or used with care.
- Other medicines with antimuscarinic effects can add to dry mouth, constipation and similar problems.
- Tell your prescriber about all your medicines, as combining several sedating medicines increases drowsiness.
Available as: Tablets and liquid taken by mouth.
Answers
Carbinoxamine: frequently asked questions
What is carbinoxamine used for?
It is an older sedating antihistamine used to ease allergy symptoms such as a runny nose, sneezing, watery eyes and itching by blocking histamine.
Why does it make me drowsy?
It is a first-generation antihistamine that crosses into the brain, so drowsiness is common; this is why it can affect driving and adds to the effect of alcohol.
Can it be given to babies?
No. Sedating antihistamines like carbinoxamine are dangerous in very young infants and must not be used in them.
Why is it not commonly used in the UK?
It is largely a US product, and in the UK newer non-drowsy antihistamines are usually preferred for allergy symptoms.
Can I drink alcohol while taking it?
It is best avoided, as alcohol adds to the drowsiness this antihistamine causes.
The wider class
About Antihistamine (sedating)
Carbinoxamine belongs to the antihistamine (sedating) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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